Insulating electrical conductors



(ModeL) J. G. SANDERSON.

INSULATING ELECTRICAL OONDUGTORS.

No. 276,891. Patented May 1,1883.

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UNITED STATES PATENT OFFICE.

J. GARDNER SANDERSON, OF SORANTON, PENNSYLVANIA.

INSULATING ELECTRICAL CONDUCTORS.

SPECIFICATION forming part of Letters Patent No. 276,891, dated May 1, 1883.

(Specimens) To all whom it may concern:

Be it known that I, J. GARDNER- SANDER SON, .a citizen of the United States, and a resident of Scranton, in the county of Luzerne and State of Pennsylvania, have invented a new and useful Improvement in Insulating Electrical Conductors, of which the following is a specification.

The object of my invention is to provide a compound for insulating electrical conductors, capable of being applied to them in a liquid condition, which afterward solidifies or hardens, retaining at the same time a certain degree of flexibility, and thus forms not only a superior insulating-covering for the conductors, but also affords a sufficient mechanical protection for the same, whereby the employin entot' special protective devices may in many instances be dispensed with.

The essential ingredients which I employ in making my improved compound are asphalt or bitumen, or other like substance, a metallic oxide which is a non-conductor of electricity, and sulphur; and the method by which I combine these substances with each other to make the product is to melt the asphalt or bitumen and to mix the metallic oxide and sulphur together after reducing each of them to a fine powder, and then incorporate them with the melted bitumen in certain proportions, after which the compound may be applied directly to the conductors, or may be run into cakes or blocks capable of being conveniently handled or transported, and which may be broken up and melted when required for use.

The accompanying drawing represents one method of applying my improved compound to a number of electrical conductors.

In preparing my improved compound I first heat the asphalt or bitumen over a slow fire in a suitable kettle or boiler for a suflicient length of time to thoroughly melt it and expel every trace of moisture. The temperature ordinarily required forthis purpose is about 300 Fahrenheit. I then by preference add to eight parts, by weight, of the asphalt or bitumen three parts of metallic oxide and three parts of sulphur. These proportions may be somewhat varied without materially atfecting the characteristics of the resultant compound. For use under some conditions the proportion of sulphur especially may be considerably re- I due-ed.

The particular metallic oxide which I prefer to use is the sesquioxide of iron, which is a non-conductor of electricity. Any metallic oxide which is a non-conductor of electricity and is capable of being reduced to a pulverulent condition may be employed as a substitute for the oxide of iron with excellent results. The metallic oxide, having been ground to a tine powder and screened through a sieve having not less than seventy meshes per lineal inch, (the finer the better,) is thoroughly mixed with an equal quantity, by weight, of flour of sulphur or sulphur in a finely-powdered condition. This mixture of sulphur and metallic oxide is slowly sifted into and thoroughly incorporated with the heated asphalt or bitumen, which should be maintained ata uniform temperature of about 300 Fahrenheit during the operation. After the materials have been thoroughly intermingled the material is ready for use, as hereinafter directed. If not designed to be used at once, I prefer to run itinto cakes or blocks of convenient size in a suitable mold, allowing it to cool and become hard therein. Such cakes may be handled and transported with facility, and may at any time be melted over a slow fire at about the same degree of heat as that employed in the original process of preparation.

It may sometimes be ditlicult to procure asphalt or bitumen of good quality, and in such case coal-tar may be employed in lieu thereof in the same proportion; or a mixture of coaltar and bitumen may be employed, the amount of coal-tar in such case being equal, or nearly so, to the amount of bitumen for which it is substituted. It will thus be understood that coal-tar and the bitumens are for the purposes of this invention equivalents. Any non-conducting metallic oxide which is capable of being reduced to powder may in either case be substituted for the sesquioxide of iron, although the latter is generally preferable.

A very convenient method of employing my improved compound for the insulation of electrical conductors, especially when placed untion, and partitions, as shown at B, which are of porcelain or other suitable non-conducting substance, perforated with suitable apertures, may be placed transversely within the trough at suitable distances apart. Uninsulated electrical conductors O are threaded through these apertures and kept under tension. The conductors being thus supported in a position parallel to but not touching each other, the insulating compound in a melted or liquid condition may be poured into the trough A, filling it to the top, as shown at D. \Vhen the compound solidifies, the conductors G will be embedded within it at the required distances from eachotherandefticientlyinsulated. Thetrough A may be made of wood or other cheap material, and may be laid at the bottom ofa trench, and after the compound has become hard may be covered with earth. The insulation of the wires will not be affected by the decay of the trough, as the compound is formed of inorganic substances, none of which are subject to change by reason of the action of the moisture ofthe earth, or from other causes. In case copper conductors are employed, their surfaces may with ad 'antage be coated with tin to prevent any possible chemical action upon the copper by the sulphur which forms a constituent of the compound.

I have described this mode of insulating underground conductors with m y im proved compound merely as an illustration of one way in Which it may be practically applied, being aware that such method of application is not new, it having heretofore been employed in connection with other and different insulating materials.

I claim as my invention 1. The hereinbet'oredescribed method or process of making an insulating compound for electrical conductors, which consists in forming a mixture of non-conducting metallic oxide and sulphur in a pulverulent condition, and incorporating said mixture with melted bitumen, substantially as set forth.

2. The hereinbefore-dcscribed compound for insulating electrical conductors. consisting of bitumen, non-conducting metallic oxide, and sulphur, combined substantially in the proportions set forth.

In testimony whereof I have hereunto subscribed my name this 2lstday of March, A. I).

Witnesses CHARLES A. TERRY, MILLER (J. EARL. 

